The three-component cocrystal 1,3,5-tri­fluoro-2,4,6-tri­iodo­benzene–pyridine N-oxide–water (1/2/1) built up by halogen bonds, hydrogen bonds and π–π inter­actions

The crystal structure of C₆F₃I₃·2C₅H₅NO·H₂O involves two highly directional C—I⋯O inter­actions, confirming pyridine N-oxide as one of the strongest acceptors for such inter­actions.

Synthesis and crystal structure of 2-amino-3-hy­droxy­pyridinium dioxido(pyridine-2,6-di­carboxyl­ato-κ³O²,N,O⁶)vanadate(V) and its conversion to nanostructured V₂O₅

2-Amino-3-hy­droxy­pyridinium dioxido(pyridine-2,6-di­car­box­yl­ato-κ³O²,N,O⁶)vanadate(V) was prepared by the reaction of VCl₃ with dipicolinic acid (dipicH₂) and 2-amino-3-hy­droxy­pyridine in water. The V^V ion is five-coordinated by one O,N,O′-tridentate dipic dianionic ligand and by two oxide ligands. Thermal decomposition in the presence of polyethyl­ene glycol led to the formation of nanoparticles of V₂O₅.

A new three-dimensional Cd^II supra­molecular framework constructed from the 1-[(1H-tetra­zol-5-yl)methyl]-1,4-di­azoniabi­cyclo­[2.2.2]octane ligand

In a new tetra­zole–cadmium(II) supra­molecular compound, each Cd^II cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from a 1-[(1H-tetra­zol-5-yl)methyl]-1,4-diazo­nia­bi­cyclo­[2.2.2]octane ligand, adopting a slightly distorted octa­hedral coordination geometry. The bridging bi­cyclo­[2.2.2]octane and chloride ligands link the Cd^II cations into one-dimensional ribbon-like N—H⋯Cl hydrogen-bonded chains along the b axis.

A two-dimensional zinc(II) coordination polymer created via in situ ligand synthesis involving C—N bond formation

The structure of a novel two-dimensional Zn^II coordination polymer, prepared by the conjugate addition reaction of 2-(1H-pyrazol-3-yl)pyridine to cis-fumaric acid in the presence of Zn(OAc)₂·2H₂O (OAc is acetate) at 413 K, exhibits two-dimensional neutral wave-like layers.

A linear heterometallic bis­muth–copper coordination polymer containing two types of organic ligands

In a linear heterometallic bismuth–copper coordination polymer, the Bi^III cation is O,N,O′-chelated by two pyridine-2,6-di­carboxyl­ate ligands and O,O′-chelated by a nitrate anion, the nine coordinating atoms conferring a tricapped trigonal prismatic environment on the metal centre. The Cu^II cation exhibits a square-pyramidal geometry. The ribbon motif propagates along the shortest axis of the triclinic unit cell and the solvent water mol­ecules are hydrogen bonded to the same ribbon.

A structural study of 4-amino­anti­pyrine and six of its Schiff base derivatives

Six derivatives of 4-amino-1,5-dimethyl-2-phenyl-2,3-di­hydro-1H-pyrazol-3-one (4-amino­anti­pyrine) have been synthesized and structurally characterized to investigate the changes in the observed hydrogen-bonding motifs compared to those in the original 4-amino­anti­pyrine. Five of the derivatives adopt the enamine tautomeric form, with the sixth derivative in the imine form.

Mixed-ligand Mn^II and Cu^II complexes with alternating 2,2′-bi­pyrimidine and terephthalate bridges

The combination of 2,2′-bi­pyrimidine and terephthalate (tpht²⁻) ligands resulted in a quite unusual coordination of tpht²⁻, with the presence of two parallel tpht²⁻ bridges in an Mn^II complex and tpht²⁻ anions coordinated as endo-bridges in a Cu^II complex.

Mononuclear and three-dimensional metal complexes based on a multidentate hydrazone ligand

Three complexes of the potentially penta­dentate hydrazone ligand N′-[1-(pyrazin-2-yl)ethyl­idene]nicotino­hydrazide were prepared by reactions with MnCl₂, Mn(CH₃COO)₂ and Cd(CH₃COO)₂. This study demonstrates that this hydrazone ligand, which can act as either a neutral or a mono-anionic ligand, is useful in the construction of inter­esting metal–organic compounds.

Two fac-tri­carbonyl­rhenium(I) aza­dipyrromethene (ADPM) complexes: ligand-substitution effect on crystal structure

Two fac-Re(CO)₃–ADPM (ADPM is an aza­dipyrromethene) complexes display distorted octa­hedral geometries, with the ADPM ligand in an equatorial position and a solvent mol­ecule (aceto­nitrile or dimethyl sulfoxide) coordinated in an axial position. The ADPM ligand shows high flexibility upon coordination, while retaining its π-delocalized nature.

The first polymorph in the family of nucleobases: a second form of cytosine

A new polymorph of cytosine is reported half a century after the report of its first known form. Cytosine thus provides the first polymorphic example in the family of nucleobases.

A three-dimensional coordination polymer based on the Zn₄(μ₃-OH)₂ unit: poly[[(μ₄-benzene-1,4-di­carboxyl­ato)bis­(μ₃-benzene-1,4-di­carboxyl­ato)bis­(μ₃-hydroxido)bis­(1,10-phenanthroline-5,6-dione)tetra­zinc] dihydrate]

A new zinc(II) coordination polymer has been prepared hydro­thermally by the reaction of Zn(NO₃)₂·6H₂O with benzene-1,4-di­carb­oxy­lic acid and 1,10-phenanthroline-5,6-dione in H₂O. Single-crystal X-ray diffraction analysis reveals that the compound possesses a three-dimensional framework with uninodal 6-connected α-Po topology.

Low-dimensional coordination polymeric structures in alkali metal complex salts of the herbicide (2,4-di­chloro­phen­oxy)acetic acid (2,4-D)

The crystals of the Li, Rb and Cs salts of the commercial herbicide (2,4-di­chloro­phen­oxy)acetic acid (2,4-D) provide examples of low-dimensional coordination polymers supported by hydrogen bonding through water mol­ecules of solvation.

Charge-assisted hydrogen bonding in salts of 2-amino-1H-benzimidazole with 3-phenyl­propynoic acid and oct-2-ynoic acid

2-Amino-1H-benzimidazolium 3-phenyl­propynoate and 2-amino-1H-benzimidazolium oct-2-ynoate crystallize in a common centrosymmetric space group. The crystal packing in both structures is influenced by N—H⋯O hydrogen bonds and their existence is confirmed by density functional theory (DFT) energy calculations.

A two-dimensional copper(II) coordination polymer based on 2-propyl-1H-imidazole-4,5-di­carb­oxy­lic acid

In the two-dimensional coordination polymer formed by copper and 5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ate, the anionic imidazole ligand acts as a bridge, connecting Cu^II cations to form a two-dimensional (4,4)-connected layer. Adjacent layers are further linked through inter­layer hydrogen-bond inter­actions, resulting in a three-dimensional supra­molecular structure.

Synthesis and crystal structure of 2-iso­cyano-4-methyl­phenyl di­phenyl­acetate: a rare case of an easily accessible odourless isocyanide

Acidic hydrogen containing 2-iso­cyano-4-methyl­phenyl di­phenyl­acetate was synthesized by the base-promoted reaction between 5-methyl­benzoxazole and di­phenyl­acetyl chloride. The achiral compound crystallizes in the chiral P2₁2₁2₁ space group. Mol­ecules are linked via C=O⋯H_phen­yl and bifurcated N C⋯H_phen­yl/N C⋯H_methine hydrogen bonds, forming one-dimensional arrays.

New isostructural transition metal complexes with a non-innocent di­thiol­ate ligand

X-ray structural analyses of three new Cu^II, Cu^III and Co^III complexes with 3,6-di­chloro­benzene-1,2-di­thiol (bdtCl₂) confirm that the four donor S atoms form a slightly distorted square-planar coordination arrangement around the central metal atom. An inter­esting finding for both the Cu^II and Cu^III complexes is that the coordination polyhedra are principally the same and differ only slightly with respect to the inter­atomic distances.

Structural and spectropscopic studies of a three-dimensional hydrogen-bonded copper(II) complex: aqua­[bis­(pyridin-2-ylcarbon­yl)amidato]­cyanido­copper(II)

In a mononuclear Cu^II complex with aqua, cyanide and bis­(pyridin-2-ylcarbon­yl)amidate ligands, the Cu^II centre is five-coordinated, forming a distorted square-planar pyramid. The UV–vis spectrum shows a d–d transition of the Cu^II centre, the electron paramagnetic resonance (EPR) spectrum confirms that the Cu^II centre has an axial symmetry coordination and cyclic voltammetric studies show two irreversible oxidation and reduction peaks.